Tablets usually consist of several inert materials, referred to as excipients, in addition to an orally active ingredient present in amounts sufficient to accomplish the desired therapeutic or nutritive effect. Tabletting excipients are generally classified according to their function, such as diluents (also called bulking agents and fillers), binders which hold the ingredients together in the compressed tablet, disintegrants which help facilitate the break-up of the tablet when placed in a fluid environment to release the active ingredient, and lubricants to improve the release of the compressed tablet from the die and punches. In addition, tablets may contain other substances intended to improve the tabletting process. For example, flow additives, flavors, sweeteners and anti-oxidants can be added.
Tabletting and some capsule filling operations are based on the ability of certain powders to bind under compression. Compressed tablets may be prepared by wet granulation, dry granulation, or direct compression. The wet granulation process typically includes mixing the components, usually in powder form, preparing the granulating binder solution, thoroughly mixing the components with the granulating binder solution to form a dough, coarse screening the mass through a sieve, drying, grinding, adding the lubricant and compressing the tablets from the resulting mixture. Dry granulation involves the steps of mixing the powder components, compressing the mixture into hard slugs, grinding the slugs into desired particle size, screening, adding other excipients if necessary, and compressing the mixture into tablets. The most preferred and economical tabletting method, direct compression, requires only two steps--mixing the dry components and compressing the mixture into tablets.
Typical direct compression binders include microcrystalline cellulose, compressible sugars, certain calcium salts, lactose and dextrose. Of these, microcrystalline cellulose has found wide commercial use. That excipient also displays good disintegration properties. However, tablets made with microcrystalline cellulose tend to have a dull rough surface. Other good binders include calcium phosphates and compressible sugars. One disadvantage of the calcium salt binders is that they do not allow the preparation of tablets with high levels of active ingredients and generally require the use of disintegrants. The sugars present a darkening problem and tend to increase in hardness with age. Mannitol and sorbitol have certain taste advantages, but they lack binding properties and require a disintegrant. They suffer too from the disadvantages of being expensive and hydroscopic.
Starch as a binder should not be confused with starch as a disintegrant or diluent since different properties are required for each use; however some modified starch binders can also function as disintegrants. The most important property required in a binder is compressibility. Generally speaking, granular starches and conventional pre-gelatinized (i.e., cooked, non-granular, cold-water-dispersible starches) do not bind well under direct compression. Cooked non-granular starches which are satisfactory as binders, are not satisfactory as disintegrants. They tend to hydrate rapidly and in many cases form a tacky film on the tablet surface, thus preventing water penetration into the tablet to aid in disintegration.
Various attempts have been made to modify starches to improve their binding/disintegration properties. These have included chemical and physical modification of the starch. Physically modified starch, partially cold-water-swelling, cold-water-soluble compacted starches are reportedly useful as binder-disintegrants for direct compression tabletting (see U.S. Pat. Nos. 3,622,677 and 4,072,535). Physically modified starches, which are cold-water-swellable, but limited in their coldwater solubility, are useful as disintegrants for various tabletting methods (see U.S. Pat. No. 4,383,111), but not as binders. Chemically modified starches such as starch ester or ether derivatives and cross-linked pregelatinized starches, are useful as disintegrants but not as binders. Starch fractions, such as non-granular amylose, are also reportedly useful as binder-disintegrants in direct compression or double compression (dry slugging) tabletting processes (see U.S. Pat. No. 3,490,742), but are not suitable as wet granulation binders.
There is, therefore, a need for a multifunctional compressible starch which is suitable for use as a binder in tabletting compositions, especially those prepared for direct compression tabletting methods.
It is one object of this invention to provide an improved tabletting composition utilizing a binder comprising small granule starch. It is another object of this invention to provide a compressed tablet utilizing a granular starch having a mean granule size of less than about 5 microns as the binder excipient. It is still another object of this invention to provide improved compressed tablets utilizing a small granule starch binder which imparts not only excellent tablet hardness, but further provides good disintegration characteristics.
Starch has also been used in many different forms for centuries as a cosmetic/body powder ingredient. In the 17th and 18th centuries wheat starch and later potato and rice starch were used for such compositions. Starch dyed in various colors was used in early England for cosmetic purposes. Starches used as body powders and more particularly as face powders gave a generally silky smooth feeling to the skin. Today the most important ingredient in most body powders in the field of human skin care is talc, a natural hydrous magnesium silicate. The excellent slip characteristics of cosmetic grade talc provides a lubricant action and a smooth feel to the touch. However, because pure talc powder does not absorb moisture well, many have employed powders consisting principally of starch and fragrance or other cosmetically functional ingredients with other added excipients to promote flowability and resistance to bacteria attack. The problem with the use of starch in cosmetic/body powders is that starches do not slip or disperse as readily as talc, thereby not giving the smooth-to-the-touch characteristic that is an important characteristic of cosmetic/body powder compositions.
The use of small granular starch, particularly amaranth or quinoa starch in cosmetic/body powder composition has been found to provide compositions having enhanced cosmetic functionality and sensory (smoothness) characteristics. Thus it is another object of this invention to improve cosmetic/body powder compositions utilizing small granule starch as a substitute for at least a portion of the talc or granular starch ingredients utilized in the cosmetic/body powder formulations now known in the art. It is still another object of this invention to provide improved cosmetic/body powder compositions comprising small granule starch in combination with at least one cosmetically functional ingredient.